It is well recognized that of prime importance in x-ray lithography, in addition to the need for good resolution, is the ability to process a large number of circuits in a short time. This dictates a short exposure time. In order to get a short exposure time generally requires increased power, which means that considerable heat is generated in the anode target ring. As a result rotating anodes are employed, which are water cooled. However, one of the problems encountered with such prior art assemblies is due to the heating of the cooling water, which changes the density, and hence the assembly becomes unbalanced creating a dynamic distribution which disturbs the exposure. After recognizing this and other deficiences of known assemblies, Applicants have directed their efforts at trying to devise an improved x-ray anode assembly which provides a dynamically balanced under all temperature conditions water cooled anode, as will become apparent as the description proceeds.
Related patents in this field include, inter alia, U.S. Pat. No. 3,743,842 issued July 3, 1973; U.S. Pat. No. 3,892,973 issued July 1, 1975; U.S. Pat. No. 4,037,111 issued July 19, 1977; U.S. Pat. No. 4,085,329 issued Apr. 18, 1978; U.S. Pat. No. 4,185,202 issued Jan. 22, 1980; U.S. Pat. No. 4,187,431 issued Feb. 5, 1980; U.S. Pat. No. 4,215,192 issued July 29, 1980; U.S. Pat. No. 4,238,682 issued Dec. 9, 1980; U.S. Pat. No. 4,301,237 issued Nov. 17, 1981 and U.S. Pat. No. 4,335,313 issued Jan. 15, 1982.